1. Field of the Invention
The present invention relates to an automated facility, and more particularly to an apparatus and a method for detecting a start signal in an automated facility, in which an introduction and a position of a pallet which has a cathode ray tube assembly and carried by a conveyor belt can be detected so that a pattern signal is automatically provided to the cathode ray tube assembly to examine and adjust the cathode ray tube assembly.
2. Description of the Prior Art
Generally, an image displaying apparatus displays various observable image signals. The image displaying apparatus including a cathode-ray tube assembly must be examined and adjusted in an automated manufacturing facility in order to display the image signals clearly.
The examination and adjustment are continuously performed for the image displaying apparatus, such as the cathode-ray tube assembly, on a pallet carried by a conveyor belt.
As known well, in a manufacturing line for adjusting the image on the image displaying apparatus, for example the cathode-ray tube assembly by providing signals for examination and adjustment to the image displaying apparatus, the cathode-ray tube assembly is introduced into the manufacturing line while it is disposed on the pallet carried by the conveyor belt. The cathode-ray tube assembly on the pallet is positioned in place to be adjacent to a measuring device. A controller receives an introduction and a position of the cathode-ray tube assembly from a detector and makes a signal a providing device that provides various signals, for examples a horizontal synchronization signal, a vertical synchronization signal, and a data channel displaying signal, from the measuring device to the cathode-ray tube assembly. At this time, a distortion of the image and a scatter of image colors can be generated in the cathode-ray tube assembly.
A worker adjusts the image on the cathode-ray tube assembly and operates a signal providing device to stop the providing of signals for the examination and adjustment from the measuring device to the cathode-ray tube assembly. Then, the pallet having the cathode-ray tube assembly thereon is carried by the conveyor belt to a next working position.
FIG. 1 is a schematic view of an apparatus for detecting a start signal in an automated facility according to the conventional art.
A cathode-ray tube assembly is examined and adjusted relating to image displayed thereon while being carried by a conveyor belt.
A pallet 10 is disposed on the conveyor belt 11, on which the cathode-ray tube assembly 12 to be examined is disposed. When the conveyor belt 11 is driven, the pallet 10 having the cathode-ray tube assembly 12 disposed thereon is carried by the conveyor belt 11.
When the pallet 10 reaches a position at which a signal providing device is mounted beside the conveyor belt, as shown in FIG. 1, the pallet 10 passes a first stopper 15 disposed between guide rails for guiding the conveyor belt and is stopped by a second stopper 16 spaced at a predetermined distance from the first stopper 15.
As shown in FIGS. 1 and 2, the first and second stoppers 15 and 16 are raised by a controller 14. While the pallet 10 is carried to an examination area in which the signal providing device is disposed, the pallet 10 comes in contact with a first limit switch 17 mounted on one of the guide rails guiding the conveyor belt 11 to be projected upward. When the pallet 10 is contacted with the first limit switch 17, the first limit switch 17 is turned on by the pallet 10 to transfer a signal for notifying an introduction of the cathode-ray tube assembly to the controller 14.
When the introduction signal is transferred from the first limit switch 17 to the controller 14, the controller 14 generates a control signal P1 to control a first solenoid valve 19.
The first solenoid valve 19 shuts off air supplied through a pneumatic hose 20 to the first stopper 15 and discharges air through a distributor 21 from the first stopper 15 so that the first stopper 15 spaced from the first limit switch 17 at a predetermined distance is lowered for about 0.3 second.
The pallet 10 carried by the conveyor belt 11 passes the first stopper 15 within 0.3 second and comes in contact with a second limit switch 18 mounted on one of the guide rails for guiding the conveyor belt 11 to be projected upward while being stopped by the second stopper 16 disposed at a position between the guide rails.
Then, the controller 14 controls the first solenoid valve 19 to supply the air which is provided through the pneumatic hose 20 to the first stopper 15 through the first solenoid valve 19 and the distributor 21. Accordingly, the first stopper 15 is raised by air pressure again.
The second limit switch 18 spaced at a predetermined distance from the first stopper 15 is turned on when being in contact with the pallet 10 and transfers a signal with respect to a position of the pallet 10 to the controller 14.
When the controller 14 receives the position signal from the second limit switch 18, the signal providing device provides a signal for examination and adjustment to the cathode-ray tube assembly 12 on the pallet 10 carried by the conveyor belt 11.
When the pallet 10 is stopped by the second stopper 16 and the second limit switch 18 detects the position of the pallet 10, the controller 14 generates a control signal P3 to control the third solenoid valve 23.
The third solenoid valve 23 provides the air supplied through the pneumatic hose 24 to a securing device 22 secured to the frame of the conveyor belt 11 according to the control of the controller 14.
The security device 22 forces the pallet 10 to be close to the worker by the air pressure of the air supplied from the third solenoid valve 23 and secures to hold the pallet 10 stable.
Then, the controller 14 generates a control signal P2 to control the second solenoid valve 25 when the pallet 10 is stably secured to the main frame.
The second solenoid valve 25 provides a pressure generator 27 of the signal supplying device such as a cylinder mounted on the main frame with pneumatic pressure through the pneumatic hose 24 according to the control of the controller 14.
The pressure generator 27 generates the pressure using the air introduced from the second solenoid valve 25 to move and connect a movable connector 28 of the signal supplying device associated with the pressure generator 27 to a secured connector 29 mounted on the pallet 10.
Thus, the pattern signals for examination and adjustment that are generated by the measuring device 13 are transferred to a printed circuit board assembly 31 of the cathode-ray tube assembly 12 through a connection cable 30, the movable connector 28, the secured connector 29, and a signal cable 33 and displayed on the cathode-ray tube 32. Accordingly, the worker can identify and adjust the pattern displayed on the cathode-ray tube 32.
When the examination and adjustment for the cathode-ray tube 32 are completed and the worker pushes a stop switch (not shown), the controller 14 controls the second solenoid-valve 25 to make the pressure generator 27 move backward. When the pressure generator 27 is moved backward, the movable connector 28 associated with the pressure generator is moved backward to be disconnected from the secured connector 29. In addition, the controller 14 controls the third solenoid valve 23 so that the secured device 22 is moved back.
On the other hand, the controller 14 controls the first solenoid valve 19 to make the second stopper 16 to be lowered for a predetermined time, for example 0.3 second, so that the pallet 10 having the cathode ray tube assembly 12 is transferred by the conveyor belt 11 as soon as the stop switch is pushed. After 0.3 second, the controller 14 controls the first solenoid valve 19 and the distributor 21 to make the second stopper 16 to be raised to an initial position again.
As described above, the cathode-ray tube assembly on the pallet which is continuously moved by the conveyor belt is provided with the pattern signals for the examination and adjustment of the cathode-ray tube.
In the apparatus for detecting the start signal in an automatic facility, when the start signal is detected from the first limit switch on the frame of the conveyor belt near the signal supplying device, the first stopper is lowered for the 0.3 second. Then, when the signal for informing the position of the pallet is detected by the second limit switch, the signal supplying device provides the cathode-ray tube assembly with the pattern signal for the examination and adjustment of the cathode-ray tube assembly. After the test for the cathode-ray tube assembly, the second stopper is lowered for the 0.3 second and is held in the initial state.
In the apparatus for detecting the start signal in the automatic facility, however, there are problems in that it is difficult to control the first and second stoppers respectively and it is also difficult to initialize the signal supplying device when errors are generated during the movement of the pallet.
In other words, when a number of pallets are continuously moved along the conveyor belt, the first pallet is pushed by the second, the third, the fourth pallets and the like to be moved fast. In the case, the first limit switch is pushed by the next pallet and cannot detect the position of the second pallet.
As described above, the signal supplying device repeatedly detects the start signal of the first limit switch. Therefore, there is another problem in that if the signal supplying device malfunctions, much elapses for supplying the signal to the cathode-ray tube assembly. Further, there is a disadvantage in that the use of the first and second limit switches needs a large space.